The present invention relates to a reflecting furnace with an ellipsoid or ellipsoidlike segment or segment portion having a first focal point in which is arranged a source of radiation and having a second focal point in which is placed the material or object to be processed.
Furnaces of the kind to which the invention pertains are usually employed for growing crystals. For example the mirror or reflecting surface furnace described in German printed patent application 22 05 558 includes two ellipsoids which heat the material to be processed from two sides. Radial symmetry obtains not in a static basis but dynamically mainly through rotation of the material and object being processed. In order to improve symmetry U.S. Pat. No. 41 84 065 describes a mirror or reflecting furnace which also includes two ellipsoids but employs an intermediate piece which separates the two ellipsoids by a particular distance. On the other hand radial symmetry is improved and still obtainable only dynamically i.e. through rotating of the object being processed.
The particular reflecting furnaces as mentioned thus far in the prior art literature are not completely those of the kind to which the invention pertains in a more stricter sense. This kind of a reflecting furnace is shown in the German patent 35 41 988 wherein particularly a modified ellipsoidal geometry is employed. Here then there is in fact a statically obtained sufficient axial and radial symmetry, provided the sample or object to be processed has the proper dimensions and is appropriately, exactly and correctly positioned. Should the axis of symmetry of the ellipsoid not coincide with the axis of the probe or sample then the heat radiation reaching the sample is no longer of radial symmetry which distorts the shape of the melting zone in an unfavorable fashion. Only if sample axis and ellipsoidal axis coincide one obtains the requisite axial asymmetry as far as the heat influx radiation is concerned so that a very limited growth length obtains.